BEIJING — With nearly a month of searching having turned up no definitive sign of missing Flight 370, Malaysia said Saturday it was overhauling the organization of its investigation and vowed to press on with efforts to find the jet.

Meanwhile, China’s state-run Xinhua news agency said a Chinese vessel in the Indian Ocean, the Haixun 01, had picked up a "pulse signal with a frequency of 37.5 kHz” — the same frequency as emitted by a plane’s flight data recorder -- but there was no confirmation that it was linked to the Malaysian Airlines jet.

A Chinese reporter aboard the Haixun 01 said the crew had relayed its findings to the authorities in Perth coordinating the search. Australian Defense Minister David Johnston told Australia's ABC News that he had not received word of the Chinese findings and urged caution.

"This is not the first time we have had something that has turned out to be very disappointing," he said late Saturday. "I'm just going to wait for … my team to come forward with something that's positive because this is a very, very difficult task."

Asked about the Chinese report, a spokesman from the command center in Perth said by phone late Saturday: "We can't verify this information at this point in time."

Weeks of false leads and official briefings with little fresh news have fed frustration among passengers’ families — particularly in China, the flight's destination — and the information vacuum has fueled speculation, rumors and conspiracy theories about the fate of the Boeing 777.

Malaysian authorities have said they believe the disappearance of the jet was the result of a deliberate act by someone on board, but have offered few specifics beyond that.

At a briefing in Kuala Lumpur on Saturday, Malyasian Defense Minister Hishammuddin Hussein staunchly defended his government’s handling of the probe, rejecting what he called “the extraordinary assertion that Malaysian authorities were somehow complicit in what happened to MH370.”

“These allegations are completely untrue,” he said.

Hussein said the government was forming three groups within the overall investigations team: an “airworthiness” panel to probe issues such as maintenance records and systems; an operations group to look into operations, meteorology and devices such as flight data recorders; and a medical and human factors group to examine issues related to psychology, pathology and survival. An independent “investigator in charge” would also be named, he said.

In addition, Hussein said Malaysia was creating three ministerial-level committees: a next-of-kin committee to provide families with information and support; a technical committee overseeing the investigatory team; and a committee tasked with supervising deployment of assets in the search.

While Malaysia remains officially in charge of the investigation, Australia, the U.S., China, Britain and France are also “accredited” members in the effort.

Flight 370 disappeared March 8 en route from Kuala Lumpur to Beijing with 239 people aboard. Search efforts are now concentrated in the Indian Ocean some 1,000 miles northwest of Perth, Australia.

Two ships — one British, one Australian — equipped with devices able to detect transmissions from a plane’s flight data recorder began searching underwater Friday along a 150-mile track where investigators believe it’s most likely the plane entered the water, Australian authorities said. One of the devices was lent by the U.S. military.

But battery life on the beacon was expected to run out within days, and the search area remains vast because so little is known about the plane’s exact movements in its final hours of flight.

On Saturday, Australian officials coordinating operations from Perth said 10 military planes, three civil jets and 11 ships were participating in the search over an area of about 84,000 square miles.

It was not immediately clear whether China’s patrol ship Haixun 01 was counted among those 11 ships, and Australian search coordinators have made no mention that any Chinese vessel participating in the search was equipped with a black-box pinger detector. Photos carried by Chinese press showed Chinese searchers in a small vessel lowered from the Haixun using a hand-held commercial pinger detector.

The command center spokesman would not discuss why Australian officials had made no mention that a Chinese ship also carried a pinger detector.

Chinese state-run media said Friday that Haixun 01 was in “a new search area north of a 1.15-million-square-kilometer area earlier designated by Australia.” The pings the Haixun 01 detected Saturday were found around 25 degrees south latitude and 101 degrees east longitude and were detected once at 3:57 p.m. local time and again around 4:30 p.m., according to a correspondent from the Jiefang (Liberation) Daily aboard the Haixun, according to the reporter aboard the Haixun.

The reporter said a pulse signal was also detected Friday afternoon for 15 minutes but there were other ships in the area and searchers were concerned that the other vessels may have been causing interference, so the crew sought to replicate their findings on Saturday.

The distance between the Haixun 01 and the British and Australian vessels searching along the 150-mile track was not immediately clear Saturday evening.

Meanwhile, a Chinese air force plane flying out of Perth also reported spotting a number of “white floating objects” in the search area Saturday and photographed them, but there was no further detail about what they were.